wip(inventory-agent): local presence advertisement and discovery using mdns almost working

adr/agent_discovery/mdns/Cargo.toml

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+[package]
+name = "mdns"
+edition = "2024"
+version.workspace = true
+readme.workspace = true
+license.workspace = true
+
+[dependencies]
+mdns-sd = "0.14"
+tokio = { version = "1", features = ["full"] }
+futures = "0.3"
+dmidecode = "0.2" # For getting the motherboard ID on the agent
+log.workspace=true
+env_logger.workspace=true
+clap = { version = "4.5.46", features = ["derive"] }

adr/agent_discovery/mdns/src/advertise.rs

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+// harmony-agent/src/main.rs
+
+use log::info;
+use mdns_sd::{ServiceDaemon, ServiceInfo};
+use std::collections::HashMap;
+
+use crate::SERVICE_TYPE;
+
+// The service we are advertising.
+const SERVICE_PORT: u16 = 43210; // A port for the service. It needs one, even if unused.
+
+pub async fn advertise() {
+
+    info!("Starting Harmony Agent...");
+
+    // Get a unique ID for this machine.
+    let motherboard_id = "some motherboard id";    
+    let instance_name = format!("harmony-agent-{}", motherboard_id);
+    info!("This agent's instance name: {}", instance_name);
+    info!("Advertising with ID: {}", motherboard_id);
+
+    // Create a new mDNS daemon.
+    let mdns = ServiceDaemon::new().expect("Failed to create mDNS daemon");
+
+    // Create a TXT record HashMap to hold our metadata.
+    let mut properties = HashMap::new();
+    properties.insert("id".to_string(), motherboard_id.to_string());
+    properties.insert("version".to_string(), "1.0".to_string());
+
+    // Create the service information.
+    // The instance name should be unique on the network.
+    let service_info = ServiceInfo::new(
+        SERVICE_TYPE,
+        &instance_name,
+        "harmony-host.local.", // A hostname for the service
+        (), // No specific IP addresses, let the daemon figure it out
+        SERVICE_PORT,
+        Some(properties),
+    )
+    .expect("Failed to create service info");
+
+    // Register our service with the daemon.
+    mdns.register(service_info)
+        .expect("Failed to register service");
+
+    info!("Service '{}' registered and now being advertised.", instance_name);
+    info!("Agent is running. Press Ctrl+C to exit.");
+
+    // Keep the agent running indefinitely.
+    tokio::signal::ctrl_c().await.unwrap();
+    info!("Shutting down agent.");
+}

adr/agent_discovery/mdns/src/discover.rs

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+use log::debug;
+use mdns_sd::{ServiceDaemon, ServiceEvent};
+
+use crate::SERVICE_TYPE;
+
+pub async fn discover() {
+    println!("Starting Harmony Master and browsing for agents...");
+
+    // Create a new mDNS daemon.
+    let mdns = ServiceDaemon::new().expect("Failed to create mDNS daemon");
+
+    // Start browsing for the service type.
+    // The receiver will be a stream of events.
+    let receiver = mdns.browse(SERVICE_TYPE).expect("Failed to browse");
+
+    println!(
+        "Listening for mDNS events for '{}'. Press Ctrl+C to exit.",
+        SERVICE_TYPE
+    );
+
+    std::thread::spawn(move || {
+        while let Ok(event) = receiver.recv() {
+            match event {
+                ServiceEvent::ServiceData(resolved) => {
+                    println!("Resolved a new service: {}", resolved.fullname);
+                }
+                other_event => {
+                    println!("Received other event: {:?}", &other_event);
+                }
+            }
+        }
+    });
+
+    // Gracefully shutdown the daemon.
+    std::thread::sleep(std::time::Duration::from_secs(1000000));
+    mdns.shutdown().unwrap();
+
+    // Process events as they come in.
+    // while let Ok(event) = receiver.recv_async().await {
+    //     debug!("Received event {event:?}");
+    //     // match event {
+    //     //     ServiceEvent::ServiceFound(svc_type, fullname) => {
+    //     //         println!("\n--- Agent Discovered ---");
+    //     //         println!("  Service Name: {}", fullname());
+    //     //         // You can now resolve this service to get its IP, port, and TXT records
+    //     //         // The resolve operation is a separate network call.
+    //     //         let receiver = mdns.browse(info.get_fullname()).unwrap();
+    //     //         if let Ok(resolve_event) = receiver.recv_timeout(Duration::from_secs(2)) {
+    //     //              if let ServiceEvent::ServiceResolved(info) = resolve_event {
+    //     //                 let ip = info.get_addresses().iter().next().unwrap();
+    //     //                 let port = info.get_port();
+    //     //                 let motherboard_id = info.get_property("id").map_or("N/A", |v| v.val_str());
+    //     //
+    //     //                 println!("  IP: {}:{}", ip, port);
+    //     //                 println!("  Motherboard ID: {}", motherboard_id);
+    //     //                 println!("------------------------");
+    //     //
+    //     //                 // TODO: Add this agent to your central list of discovered hosts.
+    //     //              }
+    //     //         } else {
+    //     //             println!("Could not resolve service '{}' in time.", info.get_fullname());
+    //     //         }
+    //     //     }
+    //     //     ServiceEvent::ServiceRemoved(info) => {
+    //     //         println!("\n--- Agent Removed ---");
+    //     //         println!("  Service Name: {}", info.get_fullname());
+    //     //         println!("---------------------");
+    //     //         // TODO: Remove this agent from your list.
+    //     //     }
+    //     //     _ => {
+    //     //         // We don't care about other event types for this example
+    //     //     }
+    //     // }
+    // }
+}
+
+async fn discover_example() {
+    use mdns_sd::{ServiceDaemon, ServiceEvent};
+
+    // Create a daemon
+    let mdns = ServiceDaemon::new().expect("Failed to create daemon");
+
+    // Use recently added `ServiceEvent::ServiceData`.
+    mdns.use_service_data(true)
+        .expect("Failed to use ServiceData");
+
+    // Browse for a service type.
+    let service_type = "_mdns-sd-my-test._udp.local.";
+    let receiver = mdns.browse(service_type).expect("Failed to browse");
+
+    // Receive the browse events in sync or async. Here is
+    // an example of using a thread. Users can call `receiver.recv_async().await`
+    // if running in async environment.
+    std::thread::spawn(move || {
+        while let Ok(event) = receiver.recv() {
+            match event {
+                ServiceEvent::ServiceData(resolved) => {
+                    println!("Resolved a new service: {}", resolved.fullname);
+                }
+                other_event => {
+                    println!("Received other event: {:?}", &other_event);
+                }
+            }
+        }
+    });
+
+    // Gracefully shutdown the daemon.
+    std::thread::sleep(std::time::Duration::from_secs(1));
+    mdns.shutdown().unwrap();
+}

adr/agent_discovery/mdns/src/main.rs

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+use clap::{Parser, ValueEnum};
+
+mod advertise;
+mod discover;
+
+#[derive(Parser, Debug)]
+#[command(version, about, long_about = None)]
+struct Args {
+    #[arg(value_enum)]
+    profile: Profiles,
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, ValueEnum)]
+enum Profiles {
+    Advertise,
+    Discover,
+}
+
+// The service type we are looking for.
+const SERVICE_TYPE: &str = "_harmory._tcp.local.";
+
+#[tokio::main]
+async fn main() {
+    env_logger::init();
+    let args = Args::parse();
+
+    match args.profile {
+        Profiles::Advertise => advertise::advertise().await,
+        Profiles::Discover => discover::discover().await,
+    }
+}